Ok, I'm baffled. I used to be able to use 1280x720 resolution, but I upgrade my Debian distro to the latest and now it refuses to use the 1280x720 resolution. Yet when I run startx -- -verbose 5 -logverbose 6 I see the following:

You should try adding the ExactModeTimingsDVI driver option, and/or the ModeValidation option. See the driver README for more information. If you need further assistance, please generate and provide an nvidia-bug-report.log.